Method of friction welding with floating workpiece fixture

ABSTRACT

This friction welding method employs a floating shroud in the tail stock of the welder that provides radial support of a workpiece having thin or fragile portions. There is limited shroud rotation relative to the tail stock during the welding process so that torsional forces generated during friction welding will not be transmitted from the workpieces through the shroud to the tail stock. This allows the workpieces to be joined without destruction or damage by the friction welding process. The shroud has a plurality of segments facilitating easy removal of the workpieces from the tail stock.

United States Pa Bonneville et a1. 4

tent 1 1 METHOD OF FRICTION WELDING WITH FLOATING WORKPIECE FIXTURElnventors: Gerald D. Bonneville, Orchard Lake; Adolf Hetke, Livonia;William N. Free, Dearborn, all of Mich.

Assignee:

Detroit, Mich.

Filed: Aug. 24, 1972 Appl. No.: 283,545

Related US. Application Data Division of Ser. No. 93,140, Nov. 27, 1970,Pat. No.

US. Cl. 29/470.3 Int. Cl B23k 27/00 Field of Search 22/470.3; 228/2;

References Cited UNITED STATES PATENTS General Motors Corporation,

Funk et a1 228/2 Oct. 9, 1973 3,442,431 5/1969 Funk et a1 228/23,571,906 3/1971 Barth et a1. 3,606,968 9/1971 Loyd Primary Examiner-J.Spencer Overholser Assistant Examiner-Ronald .1. Shore Attorney-W. E.Finken et a1.

[5 7] ABSTRACT 5 Claims, 2 Drawing Figures 1 METHOD OF FRICTION WELDINGWITH FLOATING WORKPIECE FIXTURE This application is a division of Ser.No. 93,140, filed NOv. 27, 1970, now U.S. Pat. 3,702,169.

This invention relates to friction welding and more particularly to afriction welding method in which there is floating peripheral support ofa workpiece being welded to prevent its damage or destruction duringwelding.

Friction welding has been widely employed for joining many types ofworkpieces. In many cases the robust nature of the workpieces makes themquite suitable for this process. In some cases, however, one or both ofthe workpieces being welded togetherhave relatively thin and weak partswhich do not readily lend themselves to friction welding. Providingadditional support to enable these workpieces to resist the appliedloads during welding has met with only limited success; in some cases ithas been extremely difficult to obtain proper friction welds and stillmaintain the integrity of the welded parts. The high radial andtorsional loads applied to such fragile parts have often resulted intheir severe damage or destruction. For example, the friction welding ofa rotor hub to abladed ring ofa'power turbine rotor is difficult sincethe ring is held from'rotation and its blades are relatively thin andfragile and generally must be supported at their tips duringthefrictionwelding cycle. This peripheral support is particularly necessary whenthe geometry of the weld interface consists of two mating cones disposedradially inwardly of the bladesjwhen these two parts are forced togetherduringfriction welding, a normal force is produced which causes stressesin the ring section of the bladed workpiece. To prevent yielding anddistortion of the ring section, fixed shrouds have been secured to thetail stock of the welder which contact the tips of 'the blades toprevent damage to the ring section. While such shrouds provided improvedwelds, the thin blades were subjected'to high torsional loads because ofthe construction and clearances of the stationary holding socket of thewelder and the workpiece held thereby. Thesetorsional loads sometimescaused blade distortion and damage. Furthermore, the blades often becamepress fitted within the shroud, making removal of the two welded partsfrom the tail socket quite difficult.

With thisfriction welding'methodsuch fragile workpieces can be readilywelded without damage or destruction since there is no transmittal oftangential forces through the outer portion of a workpiece beingrestrained.

In this method a free-floating shroud is employed which will support theradial loads producedduring a friction welding operation. The shroud isfree to rotate while it supports radial loads so that no tangentialforce is transmitted through the shroud to a stationary retainer. Thefloating shroud comprises a ring split so that it easily comes apart andreleases the welded work pieces after its expansion in the tail stock.The ease of part removal after welding due to the split ring design andthe floating shroud which allows the blade ring movement to eliminatethe torsional or tangential loading of the turbine blades provideimportant advancements in friction welding and particularly in themanufacture of a welded turbine rotor composite.

An object, feature and advantage of this invention is to provide a newand improved method of frictionally welding metallic workpieces togetherin which one por- 2 tion of a first workpiece is restrained fromrotation by workpiece holding means while a second portion of the firstworkpiece is allowed to turn relative to the workpiece holding means asit is being frictionally welded to a rotating second workpiece.

Another object, feature and advantage of this invention is to provide anew and improved method of frictionally welding workpieces together inwhich a central portion of a first workpiece is restrained from rotationby workpiece holding means while the outer peripheral portion ispermitted to turn a limited amount relative to the workpiece holdingmeans as it is being restrained from radial expansion and as the firstworkpiece is being frictionally welded to a second workpiece.

These and other features, advantages and objects of this invention willbecome more apparent from the following detailed description and drawingin which:

FIG. 1 is a side sectional view of a portion of a friction welder withfixtures holding the workpieces to be welded.

FIG. 2 is a front view of a work-holding ring use with the welder ofFIG. 1.

In FIG. 1 a friction welder 10 has a rotatable drive sprindle l2 drivenby a suitable motor such as that in US. Pat. No. 3,627,189 issued Dec.14, 1971, for Friction Welder to E. S. Ditto et al. The welder has ahead member 14 secured to the end of the spindle by drive keys and bybolts 16. An adapter 18 for holding a first workpiece to be welded issecured to the head member 14 by drive key 20 and by bolts 22.

The adapter has a polygonal drive socket 24 which fits thepolygonal-shaped extension 26 of a workpiece 28 which is shown as thehub of a rotor for a gas turbine engine. This hub is formed from ametallic heatresistant alloy. A central support and pilot member 30threadedly fastened to the center of the head member 14 projects axiallyto guide the rotor hub 28 into the drive socket. The pilot member has aradially-disposed, spring operated detent 32 which retains the hub inaxial position after being loaded into the drive socket.

The welder 10 has a tail stock 34 which is fixed against rotation butcan be moved back and forth on -a longitudinal axis for loading, weldingand unloading operations by a suitable motor mechanism such as thatdisclosed in the above-identified patent. The tail stock carries afixture assembly 36for holding a second workpiece 38 stationary forfriction welding. The fixture assembly has an adapter 40 secured to thetail stock by suitable keys and by bolts 42. Also there is a workpieceholder 44 secured to adapter 40by key 46 y and by bolts 48. workpieceholder 44 has a polygonal socket 50 which receives the mating polygonalshoulder 52 of a power turbine ring that forms the second workpiece 38that is to be welded to the first workpiece 28. This workpiece is inthis embodiment a power turbine ring of a heat-resistant nickel alloywhich has a plurality of evenly-spaced blades 53 extending radiallyoutwardly from the periphery of the central annular section.

The fixture includes a floating annular shroud 54 supported by the tailstock disposed around the tips of the blade to assist in supporting theworkpieces during friction welding. This peripheral support is contactedby the tips of the blades 53 during friction welding so that it reducesdistortion and possible fracture of the ring portion of workpiece 38.The shroud is preferably made in three separate segments 54a, 54b, and540 and is supported for floating or limited rotation within a retainerring 57 which is secured to the adapter 36 by a segmented clamping ring58 that extends into groove 52 formed in the adapter 36. Bolts 64threaded through the retainer ring 57 and into the clamping ring 58 maybe turned so that the clamping ring rigidly secures the retainer ring tothe adapter 40.

An annular clamp member 68 is fixed by bolt 70 to the side face of theretainer ring 57 to confine the floating shroud 54 within the retainerring 57.

To provide for axial support of the blades 50, a plurality of clamp arms72 are employed with each being secured to the outer side face of clampmember 68 by bolt 70. As shown, the end of each of these clamp arms hasan inwardly-facing block 74 of elastomeric material such as neoprenefixed thereto which contacts some of the blades 53 to provide for thedesired axial support.

As shown in the drawing, the geometry of the weld interface is providedby theinternal conical face 76 of the power turbine ring and the matingexternal conical face 78 of the hub 28. When the spindle 12 is drivenand the workpieces are forced together in a friction welding process,the high normal force produces a stress in the ring and causes the tipsof the blades 53 to contact the shroud 54. Even with this contact andradial support of the blades 38, no tangential forces will betransmitted to the stationary retainer ring 57 by the blades of thepower turbine ring in view of the fact that the shroud 54 turns alimited amount during the weld- After the welding has been completed,the tail stock is retracted with the parts welded together to anunloading position and the clamp arms 72 and clamp member 78 areremoved. The welded rotor is then removed. ln view of the fact that thering 54 is split, it easily comes apart to eliminate a press fit withthe end of the blades 50.

This invention is not limited to the details of the preferred methodshown and described for purposes of illustrating the invention for othermodifications will occur to those skilled in the art.

We claim:

1. A method of friction welding separate workpieces together comprisingthe steps of: securing a first workpiece in a first workpiece holdingfixture, securing a second workpiece in a second workpiece holdingfixture, mounting a rotatable workpiece contact member in said firstworkpiece holding fixture radially outwardly from the first workpiecesecured therein to limit the radial expansion of said first workpieceduring the friction welding of said workpieces together, relativelyrotating said workpieces at a predetermined speed, bringing saidworkpieces into contact with each other at a common interface as theyare being relatively rotated so that said interface is heated by thefrictional rubbing of said workpieces, exerting a force on saidworkpieces during welding resulting in a pressure at said interface tocause said first workpiece to expand into a terminal radial positiondetermined by the engagement of said first workpiece with said rotatablecontact member and turning said contact member relative to said firstworkpiece holding fixture by a torsional force transmittted to saidcontact member through said first workpiece as said workpieces are beingfrictionally welded together at said common interface.

2. A method of friction welding separate workpieces together comprisingthe steps of: providing a first workpiece with a recess having aperipheral wall providing a curved contact surface disposed inwardlywith respect to the outer extremities of said first workpiece, providinga second workpiece with a curved contact surface which is adapted toengage the curved contact surface of said first workpiece, securing saidfirst workpiece in a first workpiece holding fixture, securing a secondworkpiece in a second workpiece holding fixture, mounting a rotatablecontact member in said first workpiece holding fixture radiallyoutwardly with respect to the outer extremities of said first workpieceto limit the radial expansion thereof, relatively rotating saidworkpieces, relatively moving said workpieces until said curved contactsurfaces are engaged at a common interface and so that said interface isheated by the frictional rubbing of said workpieces, exerting a force onsaid workpieces as they are being frictionally welded together at saidinterface to cause said outer extremity of said first workpiece toengage and turn said rotatable contact member.

3. A method of friction welding a first workpiece having a plurality ofoutwardly projecting blades to a second workpiece comprising the stepsof: providing a central recess in said first workpiece having a conicalwall located radially inwardly from said blades, providing said secondworkpiece with a projecting conical surface which is adapted to matewith the conical wall of said first workpiece, securing said firstworkpiece in a workpiece holding fixture, securing said second workpiecein a second workpiece holding fixture,

' mounting a rotatable contact member in said first workpiece holdingfixture radially outwardly from the tips of said blades to limit theradial expansion of said first workpiece, relatively rotating saidworkpieces, relatively moving said relatively rotating workpiecesaxially until said conical wall and said conical surface engage at acommon interface, exerting a force on said workpieces as they are beingrelatively rotated so that said interface plasticizes, continuing saidforce to radially expand said first workpiece to cause the tips of saidblades to engage said rotatable contact member and turn said rotatablecontact member within said first workpiece holding fixture therebyallowing said workpieces to be frictionally welded together at saidinterface without damage to said blades as the relative rotation of saidworkpieces stops, and removing said welded workpieces from saidworkpiece holding fixtures.

4. A method of friction welding a first workpiece having a plurality ofoutwardly projecting blades to a second workpiece comprising the stepsof: providing a recess in said first workpiece having a conical wall inthe center thereof located radially inwardly from said blades, providingsaid second workpiece with a projecting conical surface which is adaptedto mate with the conical wall of said first workpiece, securing saidfirst workpiece in a workpiece holding fixture, securing said secondworkpiece in a second workpiece holding fixture, mounting a segmentedand annular contact member for turning movement in said first workpieceholding fixture radially outwardly from the tips of said blades to limitthe radial expansion of said first workpiece, relatively rotating saidworkpieces, relatively moving said workpieces along a longitudinal axisuntil said conical wall and said conical surface engage at a commoninterface, exerting an engaging force on said workpieces as they arebeing relatively rotated so that said interface will frictionally heatand plasticize, continuing said force to thereby exert a radial force onsaid blades causing the tips of said blades to engage said rotatablecontact member and turn said rotatable contact member within said firstworkpiece holding fixture thereby allowing said workpieces to befrictionally welded together at said interface without damage to saidblades, stopping the relative rotation of said workpieces and removingsaid welded workpieces from said workpiece holding fixture and from saidcontact memher.

5. A method of frictionally welding a first metal workpiece having aperipheral portion subject to torsional loading during welding to asecond metal workpiece comprising the steps of: loading said firstworkpiece in a rotatable first workpiece holding fixture, loading saidsecond workpiece in a second workpiece holding fixture, installing arotatable support for siad first workpiece in said first workpieceholding fixture radially spaced from said peripheral portion of saidfirst workpiece, securing said first workpiece holding fixture againstrotation, rotating said second workpiece holding fixture and the secondworkpiece held thereby relative to said first workpiece holding fixtureand said first workpiece held thereby, engaging said workpieces underpredetermined load at a common interface while said workpieces are beingrelatively rotated, continuing said loading and relative rotation ofsaid workpieces to expand said first metal workpiece radially until saidperipheral portion contacts and torsionally turns said r0- tatablesupport relative to said first workpiece holding fixture, stopping therelative rotation of said workpieces as said workpieces become weldedtogether, and removing said welded workpieces from said first and secondworkpiece holding fixtures and from said rotatable support.

I Inventor(s) Gerald D. Bonneville et al i 'ififii NITED STATES PATENTOFFICE v CERTIFICATE OF CORRECTION Patent INO- 3, 763, 549 QQm 9 -l2llIt is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 1,. line 45, "socket" should be stock lines 60 and 61, delete."and the floating shroud which allows the blade'ring movement toeliminate" and insert therefor in addition-to the elimination of Column2 line 62, "blade" should be. blades Column 3, line '1, after "a" insertstationary line 11, "50" should be 53 line 14, "bolt" should be boltsline 24," before "ring" insert powerturbine line 26, "38" should be 53line 35, delete "ring" and insert therefor shroud line 37, "50" shouldbe 53 Column 5, line- 20, "siad" should be said Y Signed and sealed this20th" day of Augu t 4;

":(SEAL) Attest: v I v I MGCOY M. GIBSON, JR. C. MARSHALL DANN vAttesting Officer Commissioner of Patent

1. A method of friction welding separate workpieces together comprisingthe steps of: securing a first workpiece in a first workpiece holdingfixture, securing a second workpiece in a second workpiece holdingfixture, mounting a rotatable workpiece contact member in said firstworkpiece holding fixture radially outwardly from the first workpiecesecured therein to limit the radial expansion of said first workpieceduring the friction welding of said workpieces together, relativelyrotating said workpieces at a predetermined speed, bringing saidworkpieces into contact with each other at a common interface as theyare being relatively rotated so that said interface is heated by thefrictional rubbing of said workpieces, exerting a force on saidworkpieces during welding resulting in a pressure at said interface tocause said first workpiece to expand into a terminal radial positiondetermined by the engagement of said first workpiece with said rotatablecontact member and turning said contact member relative to said firstworkpiece holding fixture by a torsional force transmittted to saidcontact member through said first workpiece as said workpieces are beingfrictionally welded together at said common interface.
 2. A method offriction welding separate workpieces together comprising the steps of:providing a first workpiece with a recess having a peripheral wallproviding a curved contact surface disposed inwardly with respect to theouter extremities of said first workpiece, providing a second workpiecewith a curved contact surface which is adapted to engage the curvedcontact surface of said first workpiece, securing said first worKpiecein a first workpiece holding fixture, securing a second workpiece in asecond workpiece holding fixture, mounting a rotatable contact member insaid first workpiece holding fixture radially outwardly with respect tothe outer extremities of said first workpiece to limit the radialexpansion thereof, relatively rotating said workpieces, relativelymoving said workpieces until said curved contact surfaces are engaged ata common interface and so that said interface is heated by thefrictional rubbing of said workpieces, exerting a force on saidworkpieces as they are being frictionally welded together at saidinterface to cause said outer extremity of said first workpiece toengage and turn said rotatable contact member.
 3. A method of frictionwelding a first workpiece having a plurality of outwardly projectingblades to a second workpiece comprising the steps of: providing acentral recess in said first workpiece having a conical wall locatedradially inwardly from said blades, providing said second workpiece witha projecting conical surface which is adapted to mate with the conicalwall of said first workpiece, securing said first workpiece in aworkpiece holding fixture, securing said second workpiece in a secondworkpiece holding fixture, mounting a rotatable contact member in saidfirst workpiece holding fixture radially outwardly from the tips of saidblades to limit the radial expansion of said first workpiece, relativelyrotating said workpieces, relatively moving said relatively rotatingworkpieces axially until said conical wall and said conical surfaceengage at a common interface, exerting a force on said workpieces asthey are being relatively rotated so that said interface plasticizes,continuing said force to radially expand said first workpiece to causethe tips of said blades to engage said rotatable contact member and turnsaid rotatable contact member within said first workpiece holdingfixture thereby allowing said workpieces to be frictionally weldedtogether at said interface without damage to said blades as the relativerotation of said workpieces stops, and removing said welded workpiecesfrom said workpiece holding fixtures.
 4. A method of friction welding afirst workpiece having a plurality of outwardly projecting blades to asecond workpiece comprising the steps of: providing a recess in saidfirst workpiece having a conical wall in the center thereof locatedradially inwardly from said blades, providing said second workpiece witha projecting conical surface which is adapted to mate with the conicalwall of said first workpiece, securing said first workpiece in aworkpiece holding fixture, securing said second workpiece in a secondworkpiece holding fixture, mounting a segmented and annular contactmember for turning movement in said first workpiece holding fixtureradially outwardly from the tips of said blades to limit the radialexpansion of said first workpiece, relatively rotating said workpieces,relatively moving said workpieces along a longitudinal axis until saidconical wall and said conical surface engage at a common interface,exerting an engaging force on said workpieces as they are beingrelatively rotated so that said interface will frictionally heat andplasticize, continuing said force to thereby exert a radial force onsaid blades causing the tips of said blades to engage said rotatablecontact member and turn said rotatable contact member within said firstworkpiece holding fixture thereby allowing said workpieces to befrictionally welded together at said interface without damage to saidblades, stopping the relative rotation of said workpieces and removingsaid welded workpieces from said workpiece holding fixture and from saidcontact member.
 5. A method of frictionally welding a first metalworkpiece having a peripheral portion subject to torsional loadingduring welding to a second metal workpiece comprising the steps of:loading said first workpiece in a rotatable first workpiece holdingfixture, loading sAid second workpiece in a second workpiece holdingfixture, installing a rotatable support for siad first workpiece in saidfirst workpiece holding fixture radially spaced from said peripheralportion of said first workpiece, securing said first workpiece holdingfixture against rotation, rotating said second workpiece holding fixtureand the second workpiece held thereby relative to said first workpieceholding fixture and said first workpiece held thereby, engaging saidworkpieces under predetermined load at a common interface while saidworkpieces are being relatively rotated, continuing said loading andrelative rotation of said workpieces to expand said first metalworkpiece radially until said peripheral portion contacts andtorsionally turns said rotatable support relative to said firstworkpiece holding fixture, stopping the relative rotation of saidworkpieces as said workpieces become welded together, and removing saidwelded workpieces from said first and second workpiece holding fixturesand from said rotatable support.